Ethnic background as a factor in TMD complaints

Objectives: The purpose of this study was to examine the possible associations between the ethnic background of TMD patients in the Netherlands and the level of TMD pain complaints and psychological/behavioral factors, while controlling for the possible interaction between ethnic and socioeconomic factors. Methods: 504 consecutive patients from the ACTA TMD clinic (mean age 40.7±14.6 yrs; 74.3% women) completed two questionnaires: 1. the RDC/TMD axis II questionnaire, including characteristic pain intensity (CPI), pain-related disability, somatisation and depression (SCL90), ethnic background, and socioeconomic status; and 2. a complementary questionnaire including oral parafunctions and perceived importance of stress in the onset and maintenance of TMD pain. Ethnic background was classified following the method of Statistics Netherlands (CBS), using the country of birth from the subject and both parents, which resulted in a classification into three subgroups: Native Dutch (ND; 69.6 %), Non Native Western (NNW; 14.8 %), and Non Native Non Western (NNNW; 15.6 %). Statistical tests used were Chi-Square, ANOVA, and Kruskall-Wallis (respective post-hoc tests: standardized residual values, Bonferroni, and Mann Whitney-U). To examine interaction effects, two-factor ANOVA was used. Results: There were no differences in age, gender, CPI, and oral parafunctions between the three ethnic groups. However, NNNW TMD patients scored higher on pain-related disability, disability days, somatisation, depression, and stress than ND and NNW patients (P<0.001). NNNW patients were more frequently unemployed, and had lower levels of education and income (P<0.001, 0.001, and 0.05, respectively). However, no interaction effects between ethnic background and socioeconomic factors in relation to the psychological variables were found. Conclusions: Ethnic background of TMD patients in the Netherlands is not associated with TMD pain complaints, but is associated with psychological variables, regardless of the patients' socioeconomic status.